code: def gen_uid(cls, session_id: str):
      return f"{session_id}_assigner"
  
file_path: mars/mars/services/scheduling/supervisor/assigner.py
imports: import asyncio
  import itertools
  import numpy
  from collections import defaultdict
  from typing import Dict, List, Set
  from ....None import oscar
  from ....core.operand import Fetch, FetchShuffle
  from ....typing import BandType
  from ...core import NodeRole
  from ...subtask import Subtask
  from ..errors import NoMatchingSlots, NoAvailableBand
label_desc: Use image node_id 1 for calling the AssignerActor obj's underlying member method code with example usage: obj.gen_uid(cls, session_id) and returns: session_id, str